#define _CRT_SECURE_NO_WARNINGS
#include<stdio.h>
int main()
{
	int k = 0;
	for (k = 'A'; k <= 'D'; k++)
	{
		if (1 == (k != 'A') + (k == 'C') + (k == 'D') + (k != 'D'))
			printf("%c", k);
	}

	return 0;
}

//as(int* A)
//{
//	*A = 0;
//}
//
//bs(int* C)
//{
//	*C = 1;
//}
//cs(int* D)
//{
//	*D = 1;
//}
//ds(int* D)
//{
//	*D = 0;
//}